title: Photostability and toxicity of pentachlorophenol and phenanthrene.
abstract: Fate of organic contaminants under UV irradiation as environmental variable was studied. Aqueous solutions of pentachlorophenol and phenanthrene were subjected to simulated solar radiation and monitored during ≤ 93 h. Immobilization tests were conducted using Daphnia magna neonates in pre-irradiated water for the assessment of photoproduct-mediated toxicity. We observed a time-dependent decrease in exposure concentrations following irradiation, which correlated positively with reduced immobilization of the animals. A complete disappearance of the lowest and highest concentrations of pentachlorophenol was noted after 25 h and 75 h, respectively. Survivorship of the animals increased until 100% and correlated positively with irradiation time. However, phenanthrene was rather persistent under irradiation, with less than 25% decline in exposure concentrations after 93 h. Neonates were not immobilized at maximum aqueous solubility of phenanthrene. Rate constants (k) for the photodegradation of pentachlorophenol at 0.41, 0.59, 1.1, and 2.1 mg l(-1) were in the range of 7.2 × 10(-2) and 4.9 × 10(-2)h(-1), showing a slight decrease with increasing initial pentachlorophenol concentration. Nonetheless, pentachlorophenol degradation in the studied concentration range could still be described by the pseudo-first-order kinetics. K values for phenanthrene at 0.12 and 0.22 mg l(-1) were 2.9 × 10(-3)h(-1) and 4.2 × 10(-3)h(-1), respectively.
authors.affiliation: Department of Biology, University of Eastern Finland, Joensuu Campus, PO Box 111, FI-80101 Joensuu, Finland. Stanley.Agbo@uef.fi
authors.forename: Stanley O
authors.initials: SO
authors.lastname: Agbo
authors.forename: Eberhard
authors.initials: E
authors.lastname: Küster
authors.forename: Anett
authors.initials: A
authors.lastname: Georgi
authors.forename: Jarkko
authors.initials: J
authors.lastname: Akkanen
authors.forename: Matti T
authors.initials: MT
authors.lastname: Leppänen
authors.forename: Jussi V K
authors.initials: JV
authors.lastname: Kukkonen
mesh_terms: D000818:Animals; D003621:Daphnia; D004785:Environmental Pollutants / Q000528:radiation effects / Q000633:toxicity*; D007700:Kinetics; D010416:Pentachlorophenol / Q000528:radiation effects / Q000633:toxicity; D010616:Phenanthrenes / Q000528:radiation effects / Q000633:toxicity; D010782:Photolysis; D018675:Toxicity Tests; D014466:Ultraviolet Rays
chemical_list: D004785:Environmental Pollutants; D010616:Phenanthrenes; C031181:phenanthrene; D010416:Pentachlorophenol